DE102007001237B4 - System and method for controlling autoignition - Google Patents

Abstract

A method of operating an engine (10) of a vehicle, the engine comprising a cylinder (30) with at least first and second valves (52a, 52b), the method comprising:
during a first mode, the first valve (52a) operates actively and the second valve (52b) deactivates during a cycle of the cylinder (30), during the first mode the cylinder (30) operates to provide at least air during an intake stroke can enter the cylinder (30) where the air is mixed with fuel and compressed to achieve auto-ignition; and
during a second mode, the first and second valves (52a, 52b) operate actively during one cycle of the cylinder (30), while during the second mode the cylinder (30) operates to allow at least air to enter the cylinder (30) where the air is mixed with fuel and ignited by a spark plug (92);
during a transition from the first mode to the second mode, the second valve (52b) is activated and the first valve (52a) is kept active, the first and second valve (52b) inlet valves (52a, 52b) of the cylinder (30) are.

Description

General state of the art and brief presentation

To improve overall engine performance, engines can use different combustion modes across different working conditions. For example, spark ignition (SI) combustion can be used in some circumstances, while controlled auto-ignition (CAI) or homogeneous charge ignition compression (HCCI) can be used in other conditions. In some cases, different valve timing and / or valve lift is used when working in these different modes. The different valve operation can enable the engine to reliably achieve the desired type of ignition or combustion while at the same time meeting emission and performance goals.

One approach to providing different valve operation in different combustion modes is in US 6 640 771 B2 described. In this example, several intake valves with different stroke profiles are operated in different combustion modes. In addition, in one example, at least two intake valves are provided in each cylinder, wherein one intake valve can be changed between a first and second stroke and the other intake valve can be actuated to an OFF position with the aid of a valve shutdown device. Thus, each intake valve switch changes an effective valve lift in different modes.

The inventors of the present invention have recognized disadvantages with such an approach. In particular, because each valve has switchable valve operation to provide the various stroke profiles and there are multiple valves per cylinder, each cylinder may require multiple actuators. In multi-cylinder engines, such an increased number of actuators can lead to increased system costs and increased weight. In addition, the increased number of actuators may require increased hydraulic pressure or hydraulic capacity in the case of hydraulic actuators, potentially increasing weight and cost.

In one approach, the above problems can be addressed by a method of operating an engine of a vehicle, the engine having a cylinder with at least a first and a second valve, the method comprising: working actively with the first valve and during a first mode the second valve is deactivated during a cycle of the cylinder, during the first mode the cylinder operates to at least allow air to enter the cylinder during an intake stroke where the air is mixed and compressed with fuel to achieve auto-ignition; and during a second mode, the first and second valves operate actively during one cycle of the cylinder, during the second mode the cylinder operates to allow at least air to enter the cylinder where the air is mixed with fuel and via a spark of one Spark plug is ignited.

A method of the type described above, for example, discloses the German published application DE 10 2005 031 241 A1 , The US 5,301,636 A describes an associated system for operating an engine of a vehicle and thus a system for performing the method.

According to the invention, during a transition from the first mode to the second mode, the second valve is activated and the first valve is kept active, the first and second valves being intake valves of the cylinder.

In this way it is possible to provide a transition between different stroke profiles when the combustion is switched from compression ignition or compression ignition to spark ignition by simply activating the second valve (although changes in other valve operation may also be used if necessary).

list of figures

• 1 shows an exemplary engine cylinder configuration;
• 2A-B show a detailed view of exemplary combustion chambers;
• 2C shows an exemplary detailed view of a plunger for use with the example of FIG 2 B ;
• 3 illustrates exemplary lift profiles and
• 4-6 Figure 14 shows high level flow diagrams for performing exemplary system operation.

Detailed description

1 shows a cylinder of a multi-cylinder engine and the intake and exhaust path connected to this cylinder. Continue with 1 becomes a direct injection internal combustion engine 10 , which comprises several combustion chambers, from one electronic motor controller 12 controlled. The combustion chamber 30 of the motor 10 is shown to have combustion chamber walls 32 contains, being a piston 36 positioned in it and with a crankshaft 40 connected is. A starter motor, not shown, is connected to the crankshaft via a spring wheel, not shown 40 coupled. The combustion chamber or the cylinder 30 is shown in such a way that it can be accessed via (not shown, see 2 ) Intake valves 52a and 52b and (not shown, see 2 ) Exhaust valves 54a and 54b with an intake manifold 44 and an exhaust manifold 48 communicates. A fuel injector 66A is directly to the combustion chamber 30 Coupled shown to be directly injected fuel proportional to the pulse width of the controller 12 via an electronic driver 68 receive received signal fpw. The fuel injector may be mounted on the inside of the combustion chamber or in the top of the combustion chamber (as an example). Fuel becomes the fuel injector 66A supplied by a conventional high pressure fuel system, not shown, which includes a fuel tank, fuel pumps and a fuel rail.

The intake manifold 44 is shown so that it has a throttle plate 62 with a throttle body 58 communicates. In this particular example, the throttle plate is 62 like an electric motor 94 coupled that the position of the throttle plate 62 from the controller 12 about the electric motor 94 is controlled. This configuration is commonly referred to as Electronic Throttle Control (ETC), which is also used during idle control. In an alternative embodiment, not shown, which is well known to those skilled in the art, a bypass air passage is parallel to the throttle plate 62 arranged to control intake air flow during idle control via a throttle control valve positioned within the air passage.

An exhaust gas sensor 76 is on the exhaust manifold 48 in front of a catalyst 70 shown coupled. Note that the sensor 76 depending on the outlet configuration as below 1B described corresponds to different different sensors. The sensor 76 can be any of many known sensors for providing an indication of an exhaust air / fuel ratio such as a linear or UEGO (Universal or Wide-Range Exhaust Gas Oxygen), a dual state oxygen sensor or EGO, a HEGO (Heated EGO) , a NOx, HC or CO sensor.

The ignition system 88 delivers SA (Spark Advance) from the controller under selected work modes in response to a pre-ignition signal 12 a spark over the spark plug 92 to the combustion chamber 30 , Although spark ignition components are shown, the engine can 10 (or a portion of the cylinders thereof) operate in a compression ignition mode with or without ignition assistance, as discussed in more detail below. In addition, in an alternative embodiment, the combustion chamber has no spark plug.

The controller 12 can be configured to cause the combustion chamber 30 works in various combustion modes as described herein. Fuel injection control can be varied to provide different combustion modes along with other parameters such as EGR, valve control, valve operation, valve deactivation, etc.

Behind the catalytic converter 70 is an adsorbent or storage 72 shown for nitrogen oxide (NOx) positioned. The NOx storage 72 is a three way catalyst that adsorbs NOx when the engine 10 is operated lean stoichiometric. The adsorbed NOx is subsequently reacted with HC and CO and catalyzed when the controller 12 causes the engine 10 works either in a rich homogeneous mode or in an almost stoichiometric homogeneous mode. Such operation occurs during a NOx purging mode when stored NOx is to be purged from the NOx reservoir 72 or during a steam purging cycle to fuel vapors from the fuel tank 180 and the fuel vapor storage canister 184 via a purge control valve 168 recover, or during work modes that require more engine power, or during work modes that control the temperature of emission control devices such as catalytic converter 70 or regulate NOx storage. It is understood that different different types and configurations of emission control devices and purging systems can be used.

The controller 12 is in 1 shown as a conventional microcomputer which is a microprocessor unit 102 , Input / output ports 104 , an electronic storage medium for executable programs and calibration values, in this specific example as a read-only memory chip 106 shown a random access memory 108 , a maintenance memory 110 and contains a conventional data bus. The controller 12 is shown to send various signals to the engine 10 coupled sensors in addition to those already discussed, including a measurement of mass air flow (MAF) from one to a throttle body 58 coupled air mass flow sensor 100 ; Engine coolant temperature (ECT) from one to a cooling sleeve 114 coupled temperature sensor 112 ; a profile ignition pickup signal from one to the crankshaft 40 coupled Hall effect sensor 118 (or another type of sensor); and throttle position (TP) from a throttle position sensor 120 and an absolute manifold pressure signal (MAP) from the sensor 122 , The engine speed signal RPM is from the controller 12 generated from the signal PIP in a conventional manner, and the manifold pressure signal MAP from a manifold pressure sensor provides an indication of the vacuum or pressure in the intake manifold. Note that various combinations of the above sensors can be used, such as a MAF sensor without a MAP sensor, or vice versa. During stoichiometric operation, this sensor can provide an indication of the engine torque. In addition, this sensor, together with the engine speed, can provide an estimate of the fill quantity (including air) let into the cylinder. In one example, the sensor produces 118 , which is also used as an engine speed sensor, a predetermined number of equally spaced pulses every revolution of the crankshaft.

In this example, the temperature Tcat1 of the catalyst 70 and the temperature Tcat2 of the emission control device 72 (which may be a NOx trap) derived from engine operation as from U.S. Patent No. 5,414,994 is known, the specification of which is incorporated herein by reference. In an alternative embodiment, the temperature Tcat1 from the temperature sensor 124 delivered and the temperature Tcat2 from the temperature sensor 126 delivered.

Continue with 1 is the engine 10 with an intake camshaft 130 and an exhaust camshaft 132 shown with the camshaft 130 both intake valves 52a , b actuated and camshaft 132 both exhaust valves 54a , b operated. The valves can be adjusted using stroke profiles (see 2 ) are operated on the camshafts, where the stroke profiles between the various valves can vary in terms of height, duration and / or timing. However, alternative camshaft arrangements (overhead and / or push rod) could be used if necessary.

In one embodiment, with regard to 2A In more detail, a deactivatable tappet can be located in the valve stem of one or more of the intake and exhaust valves 52 and 54 can be used to obtain individual valve deactivation under selected working conditions. In this example, the plunger can have an idle stroke action, for example. 2 B however, shows an alternative example in which an alternative deactivatable plunger is shown in which only a part of the plunger is deactivated. In one example, the cam timing can also be controlled by actuators 136 and 138 can be varied based on working conditions. The actuators can be driven hydraulically or electrically, or combinations thereof. A signal line 150 can send a valve timing signal to the unit 136 send and receive a cam timing measurement. The signal line can be analog 152 a valve timing signal to the unit 138 send and receive a cam timing measurement.

The processed sensor output signal from the sensor 160 can provide an indication of both the oxygen concentration in the exhaust gas and the NOx concentration. For example, provides signal 162 the controller a voltage that indicates the O ₂ concentration while signal 164 provides a voltage indicative of the NOx concentration. Alternatively, the sensor 160 a HEGO, UEGO, EGO or other type of exhaust gas sensor. Note also that, as above with regard to sensor 76 described, the sensor 160 can correspond to different different sensors depending on the system configuration.

As described above, shows 1 only one cylinder of a multi-cylinder engine, and that each cylinder has its own set of intake / exhaust valves, fuel injectors, spark plugs, etc. In an alternative embodiment, an intake port injection configuration may be used where a fuel injector is attached to the intake manifold 44 in a channel instead of directly to the cylinder 30 is coupled.

In addition, in the disclosed embodiments, an exhaust gas recirculation (EGR) system directs a desired portion of the exhaust gas from the exhaust manifold 48 to the intake manifold 44 via an EGR valve, not shown. Alternatively, part of the combustion gases in the combustion chambers can be recovered by controlling the exhaust valve timing.

The motor 10 works in various modes including lean operation, rich operation and "almost stoichiometric" operation. “Almost stoichiometric” operation refers to an oscillating operation around the stoichiometric air-fuel ratio. As a rule, this stoichiometric operation is regulated by feedback from exhaust gas oxygen sensors. In this almost stoichiometric mode of operation, the engine is operated within an air-fuel ratio of 1 of the stoichiometric air-fuel ratio. This vibrating operation is usually in the The order of 1 Hz, but can vary faster and slower than 1 Hz. In addition, the amplitudes of the vibrations are generally less than 0.35 A / F from stoichiometric operation; but can be larger under different working conditions. Note that this vibration need not be symmetrical in terms of amplitude or time. Note further that an air-fuel preset may be included, the preset being set slightly lean or rich in stoichiometry (eg, within an air-fuel stoichiometric ratio of 1). Note also that this default and the lean and rich vibrations can be controlled by an estimate of the amount of oxygen stored in upstream and / or downstream three-way catalysts.

As described below, air-fuel ratio feedback control is used to provide almost stoichiometric operation. In addition, feedback from exhaust gas oxygen sensors can be used to control the air-fuel ratio during lean and rich operation. In particular, a switching type HEGO (Heated Exhaust Gas Oxygen Sensor) can be used for stoichiometric control of the air-fuel ratio by controlling the injected fuel (or additionally air via throttle valve or VCT) based on feedback from the HEGO sensor and the desired air-fuel ratio. In addition, a UEGO sensor (which provides a substantially linear output over an exhaust air-fuel ratio) can be used to control the air-fuel ratio in lean, rich, and stoichiometric operation. In this case, fuel injection (or additional air via throttle or variable valve timing or control which and a series of intake and / or exhaust valves that are active) is based on a desired air-fuel ratio and the air-fuel ratio. Ratio set by the sensor. In addition, an air-fuel ratio control could be used for individual cylinders if necessary.

Moisture detection may also be used in conjunction with the illustrated embodiments. For example, is a sensor 140 shown for absolute or relative humidity to measure the humidity of the ambient air. This sensor could either be in the manifold 44 incoming inlet flow or measure ambient air flowing through the engine compartment of the vehicle. In addition, in an alternative embodiment, a second moisture sensor ( 141 ) shown, which is located inside the vehicle and to a second controller 143 is coupled via lines 145 with the controller 12 communicated. The control processes described below can be done in the controller 12 or in the controller 143 or a combination of them. Note also that the interior humidity sensor can be used in an automatic climate control that controls the climate in the passenger compartment of the vehicle. In particular, it can be used to control the air conditioning system and, in particular, to determine whether the air conditioning compressor clutch, which couples the compressor to the engine, in order to operate the processor, releases or blocks it.

Note also that moisture can be estimated or derived from various working parameters such as air pressure. Alternatively, the moisture can be derived on the basis of auto-ignition characteristics in [Lakune] via adaptive learning. In addition, air pressure and adaptive learning can be used in combination and also with recorded moisture values.

As described in more detail below, engine combustion can occur 10 of different types / modes, depending on the working conditions. In one example, spark ignition (SI) may be used when the engine uses an igniter, such as a spark plug coupled in the combustion chamber, to control the combustion chamber gas timing at a predetermined time after the top dead center of the combustion stroke. In one example, in spark ignition operation, the temperature of the air entering the combustion chamber is significantly lower than the temperature required for auto-ignition. While SI combustion can be used over a wide range of engine torque and speed, it can produce increased concentrations of NOx and lower fuel efficiency compared to other types of combustion.

Another type of combustion from the engine 10 HCCI (Homogeneous Charge Compression Ignition) or CAI (Controlled Auto-Ignition) can be used, where combustion chamber gases auto-ignite at a predetermined time after the compression cycle of the combustion cycle or near the top dead center of the compression. Typically, when compression ignition is used from a premixed charge of air and fuel, fuel is usually premixed homogeneously with air, such as in an engine with intake port injection and spark ignition, or with directly injected fuel during an intake stroke but with a high proportion of air Fuel. Since the air-fuel mixture is heavily diluted by air or residual exhaust gases, which leads to lower combustion gas peak temperatures, the production of NOx can be reduced compared to the concentrations found in SI combustion. In addition, fuel efficiency when working in a compression combustion mode can be increased by reducing engine pumping loss, increasing the gas specific heat ratio, and using a higher compression ratio.

In compression ignition mode, it may be desirable to have tight control over the timing of the auto-ignition. The initial intake fill temperature directly affects the auto-ignition timing. The start of the ignition is not directly controlled by an event such as the injection of fuel in the standard diesel engine or the ignition of the spark plug in the spark ignition engine. In addition, the rate of heat release is controlled neither by the rate nor by the duration of the fuel injection process as in the diesel engine nor by the propagation time of the turbulent flame as in the spark ignition engine.

Note that auto-ignition is also a phenomenon that can cause knock in an spark-ignition engine. Knocking can be undesirable in spark-ignition engines because it increases heat transfer within the cylinder and can burn or damage the piston. In a controlled compression ignition operation with its high air-fuel ratio, knocking does not normally result in engine deterioration because the diluted charge keeps the rate of pressure rise low and the maximum temperature of the burned gases relatively low. The lower rate of pressure increase mitigates the harmful pressure vibrations characteristic of spark ignition knock.

Compared to a spark ignition engine, the temperature of the filling quantity can usually be raised at the beginning of the compression stroke in order to achieve auto-ignition conditions at or near the end of the compression stroke. Those skilled in the art will understand that numerous other methods can be used to raise the initial fill temperature. Some of these include: heating the intake air (heat exchanger), keeping part of the warm combustion products in the cylinder (internal EGR) by adjusting the intake and / or exhaust valve timing, compressing the intake charge amount (turbocharging or charging), changing the auto-ignition characteristics and the like Engine supplied fuel and warming the intake air charge (external EGR).

During HCCI combustion, the auto-ignition of the combustion chamber gas can be controlled to occur at a desired position of the piston or crank angle to produce a desired engine torque, and so it may not be necessary to initiate a spark from an ignition mechanism for it comes to combustion. However, late spark plug timing after an auto-ignition temperature should have been reached can be used as a backup ignition source in the event that auto-ignition does not occur.

A third type of combustion by the engine 10 may be carried out, such as in the case where a spark device is included, uses the spark device to initiate (or assist) combustion when the temperature of the combustion chamber gas approaches auto-ignition temperature (e.g., a level substantially near auto-ignition reached without incineration). Such a type of spark assisted combustion can have increased fuel efficiency and reduce NOx production compared to SI combustion, and still operate in a higher torque range compared to HCCI combustion. The spark assist can also offer an overall larger window for controlling the temperature at a specified timing in the engine cycle. In other words, without spark assistance, a small change in temperature can result in a fairly large change in combustion timing control, which affects engine output and performance. In spark assist mode, it is possible to get many of the benefits of HCCI combustion, but rely on spark timing to provide the final energy needed to auto-ignite and thus control combustion timing more precisely. Thus, in one example, spark support can also be used during transitions between SI combustion and HCCI under some conditions.

In one embodiment, spark assist mode may be used where a small amount of fuel is supplied to the gases near the spark plug. This small cloud of fuel can be used to allow the flame to spread better and create increased pressure in the cylinder, thereby initiating auto-ignition of the remaining air-fuel mixture. Thus, a relatively small cloud of richer gases can be used that are near the spark plug, which can also be homogeneous, stratified, or slightly stratified. One approach to providing such operation can be to use a second direct fuel injection in the compression stroke.

An example of an application that includes at least the three combustion modes presented above may include using SI for starting and / or after engine starting during an engine warm-up period. After such engine cranking and warming up, the combustion process can transition to HCCI combustion for improved fuel economy and emissions through spark assisted combustion. During periods when high engine torque is required, spark assist can be activated to ensure proper combustion timing. When the engine returns to the request for low or moderate torque, the involvement of the spark assist can end to realize the full benefits of HCCI.

As noted above, ambient humidity of air drawn into the engine during the intake stroke can affect the combustion temperature by diluting the fill with material that cannot be oxidized and because the specific heat of water is higher than that of air. Thus, with increasing moisture, in order to obtain a desired autoignition timing, the initial fill temperature should be adjusted according to moisture concentrations. For example, the use of moisture detection or estimation may thus allow for improved settings on multiple engine working parameters to help achieve or maintain HCCI combustion even when a vehicle is experiencing varying levels of ambient humidity. Thus, increased humidity may require higher starting temperatures, and lower humidity may require a lower starting temperature for a given auto-ignition timing at a given speed and torque.

The ambient humidity of the air drawn into the engine during the intake stroke also affects peak combustion temperatures because it has a higher specific heat than air, the more common diluent. As the ambient humidity of the air drawn into the engine during the intake stroke increases, the combustion peak temperature decreases via a dilution of the charge with material that cannot be oxidized and consequently raises the required initial charge temperature to achieve efficient HCCI combustion. The relative or ambient humidity can be measured using sensors 140 and or 141 determined or derived from other data and the motor controller 12 be reported to determine the ideal settings for engine control parameters for efficient operation.

Note that several other parameters can affect both the peak combustion temperature and the temperature required for efficient HCCI combustion. These and any other applicable parameters can be found in the in the motor controller 12 embedded routines are taken into account and used to determine optimal working conditions. For example, as the octane number of the fuel increases, the required peak compression temperature may increase because the fuel requires a higher peak compression temperature to achieve ignition. In addition, the level of fill dilution can be affected by a variety of factors, including both moisture and the amount of exhaust gases present in the inlet fill. In this way, engine parameters can be adjusted to compensate for the effect of moisture variation on auto-ignition, ie the effect of water makes auto-ignition less likely.

While one or more of the above combustion modes can be used in some examples, other combustion modes, such as stratified operations, can be used, either with or without spark-initiated combustion.

As noted here, in one example of a compression or auto ignition engine, the intake valve (s) are actuated by either a higher or lower lift cam profile depending on the combustion mode selected. The low lift cam profile is used to trap a large amount of residual gas (exhaust gas) in the cylinder. The trapped gases, in some examples, promote compression or autoignition by increasing the initial fill temperature. However, in the spark ignition mode (either high or low loads), the high lift cam profile is used. Such a switchable cam profile can be achieved by various cam and tappet systems, which switch, for example, between an inner and an outer web. Switching can be accomplished by oil flow hydraulic actuators, which may require a stronger flow oil pump, potentially increasing weight and cost, and reducing efficiency (for example, a stronger flow oil pump may result in greater capacity loss due to increased oil volume and potential problems with respect to it) a lack of sufficient flow in the oil lines). As another example, such systems can involve an increased number of rams and higher machining costs.

Thus, in another embodiment, instead of using a cylinder with a single intake valve (or multiple switchable intake valves) that switches between different profiles, a cylinder with at least two intake valves can be used, each of the valves having a different lift profile (at least for this Cylinder). During compression or auto-ignition, an intake valve with a higher and / or longer stroke can be blocked by using a collapsible plunger, while an intake valve with a lower and / or short stroke remains active. During spark ignition, the higher / longer stroke intake valve may operate to increase airflow in the engine while the lower / shorter stroke intake valve continues to operate.

Due to the fact that in this example only half of the valves now need to be switched, the oil flow requirements for valve actuation are significantly reduced, thereby reducing the overall oil flow requirements of the engine system. If the valve is considered harder, only half of the shocks are switchable units in this example, and the camshaft can be manufactured using a cheaper manufacturing process with considerably less machine processing. In addition, the oil pump can have a lower work flow rate, which reduces costs, and lower parasitic losses. In this way, system costs can be reduced while still getting spark, compression or auto ignition along with transitions in between.

Active valve operation can refer to the opening and closing of the valve during a cycle of the cylinder, where deactivated valves can be held in a closed position (or held in a fixed position for the cycle) for one cycle of the cylinder.

While the above examples illustrate the benefits of a particular situation, the present approaches can be applied to a variety of different systems and configurations, such as exhaust systems, as well as systems with more than two intake or two exhaust valves per cylinder.

Returning to an exemplary intake valve system, the first intake valve may have a lower lift profile that is inherently capable of allowing sufficient air to flow for the engine to operate in compression or auto-ignition. In addition, the first inlet valve can have a valve timing control (fixed or adjustable) set for compression or auto-ignition. The second intake valve may have a valve lift and / or valve timing (fixed or adjustable) that supplies the rest of the air for spark ignition, in addition to the air required for compression or auto-ignition, as in the example of FIG 3 shown.

The valve can be deactivated via switchable tappets which are attached to a valve with a higher / longer stroke, which in one example is only active during spark ignition operation. During compression or auto-ignition, the plunger can deactivate so that the valve remains closed with a higher / longer stroke during one cycle of the cylinder. The lower / shorter stroke valve may be permanently active to open and close during one cycle of the cylinder to provide either all of the air during compression or auto-ignition or part of the air to spark-ignite.

However, in another embodiment, the higher / longer stroke intake valve may be deactivated under conditions other than compression or auto-ignition, such as during a vehicle deceleration to reduce airflow during fuel shutdown during the deceleration, or under other conditions , In addition, various valves have been designated to have a higher or shorter stroke, which can be identified by a maximum valve stroke or an average valve lift height (opening into the cylinder). Likewise, valves with a shorter or longer stroke can be identified, for example, by a crank angle opening period, even if the valves may open and / or close earlier or later during the cylinder cycle.

Now referring to 2A it shows an exemplary cylinder configuration in which two intake valves ( 52a and 52b) of the cylinder 30 of the motor 10 via a common camshaft 130 each with a different cam profile 210 and 212 are operated, examples of which with regard to 3 are described in more detail. The figures show that valve 52a has a longer and higher valve lift profile than 52b. With this example valve 52b over a pestle 216 actuated while valve 52b via a collapsible plunger 214 is activated by a controller 12 can be controlled.

2A also shows two exhaust valves 54a and 54b , also via profiles 220 and 222 by pestle 224 and 226 actuated, plunger 224 from the controller 12 can be deactivated. In this example, the valve is shown to have a longer and higher valve lift than the valve 54b having.

Although this example shows an overhead camshaft engine with a tappet coupled to the valve stem, tappets can also be used with a bumper motor, and a collapsible tappet can thus be coupled to a bumper.

The diagram of 2A only one cylinder of the engine 10 , the engine may be a multi-cylinder engine, each cylinder being the same or similar to that in 2A shown or different from this. While the above valve system can have advantages in an engine with compression or auto ignition, it can also be used in other engine combustion systems.

Now referring to 2 B it shows an alternative configuration of camshaft and tappet.

In this example in particular, the shear profile is 210 in lifting sections 210A and 210C and a zero stroke section 210B divided. The plunger is activated during active valve operation 284 as a unit of profiles 210A and 210C pressed, and during the deactivation is an outer section of 284 decoupled from an inner section, as in 2C described so that valve 52a is not activated. The stroke is analog 220 similarly divided, and pestle 294 is similar to the pestle 284 , Thus, an alternative approach to deactivation is shown, with which one can achieve improved manufacturability, for example. Note also that a single profile such as 210A can be used instead of the double profile shown ( 210A and 210C) ,

In particular shows 2C an alternative deactivatable plunger, in which a locking pin 254 used to the inner section 252 to the outer section 250 to couple or to decouple from it. When the pin is in the locked position, it does so by contact with the profiles 210A and 210C caused movement that the inner portion follows the movement and thus actuates the valve stem and the valve coupled to the inner portion. Alternatively, when the pin is in the unlocked position, an idle lift spring acts in the inner section 256 that the outer section 250 separate from the inner section 252 emotional. Because the profile 210B that with the inner section 252 is in contact, has less or no stroke, the valve remains essentially closed, and thus the cylinder can be deactivated. The pencil 254 can be operated via hydraulic pressure controlled by a hydraulic valve communicating with a controller (in one example).

In this way, an alternative approach using a deactivatable plunger can be used, in which the producibility of the plunger is increased and at the same time the desired effect is maintained.

Finally, further examples of valve deactivation can optionally be used.

Now referring to 3 it shows an exemplary stroke profile of the valve at 310 52b , wherein the profile can be used to provide a desired fresh air charge and remaining charge to improve compression or auto-ignition, such as by providing a higher initial charge temperature at the start of compression. As noted here, the valve needs one example 52b to have no deactivation mechanism. 3 also shows at 312 an exemplary stroke profile of the valve 52a , wherein the profile can be used to provide a desired operation for spark ignition operation. In the example of 3 assigns the profile 312 some lifting sections that are higher than that of 310 , and also a longer stroke than that of 310 , As noted here, valve 312 can be selectively deactivated via a deactivatable plunger during compression or auto-ignition operation.

If both intake valves are active, an effective stroke profile can be achieved 314 can be achieved, whereas the profile 310 while controlling compression or autoignition, at least in one example.

Now referring to 4 FIG. 4 shows a high level flow diagram of an exemplary routine for selecting an engine work mode based on work conditions. at 410 the routine determines whether the engine is currently starting when the temperature is below a preselected value. The temperature may be an engine coolant temperature, an ambient air temperature, an engine oil temperature, a transmission oil temperature, combinations thereof, or others. If so, the routine continues 412 to select spark ignition combustion for all of the engine cylinders so that the engine is started with spark ignition combustion. Otherwise the routine continues 413 to determine a desired engine output such as a desired engine or wheel torque based on a driver request, traction control, vehicle speed control, vehicle stability control, combinations thereof, or others. Next, the routine determines 414 whether there are conditions to allow compression or auto-ignition. Such conditions can include temperatures (such as 410 noted), manifold pressure, fuel vapor storage or regeneration status, humidity, vehicle speed, combinations thereof, or other.

If the answer to 414 No, the routine continues 412 , Otherwise the routine continues 416 to determine whether the desired engine output and engine speed are within a specified compression or auto-ignition window. Note that the window may have hysteresis, for example, to reduce excessive switching between modes. In addition, the window can vary with other working conditions (as an example).

at 418 The routine determines whether one or more cylinders (and the number of such cylinders) should be operated with compression or auto-ignition, with spark ignition selected for any remaining cylinders.

For example, the routine may select a number of compression or auto-ignition cylinders based on the desired torque output, transmission condition, etc.

From either 412 or 418 the routine continues 420 to determine whether the particular or selected cylinder combustion mode for each of the cylinders is different from the cylinder's current combustion mode. If so, there will be a transition for one or more cylinders in 422 carried out, exemplary details of which are given in 5 are described in more detail. For example, if multiple cylinders are to have a transition from one combustion mode to another, the cylinders may make the transition in a single engine cycle, or the transition of cylinders may extend over a longer period of time to reduce any driver indication that a transition is in progress ,

Now referring to 5 determined at 510 the routine of whether a transition should be made for one or more cylinders. If so, the routine continues 512 to determine a duration over which the transition should take place. Then the routine determines in 514 whether there are one or more transitions to spark ignition combustion to be performed. If so, the routine continues to 516, otherwise the routine continues to 518.

Note that if some cylinders are to spark spark and some spark spark, the routine of 514 can be repeated on an individual cylinder basis (as an example). In this way, the engine can be operated so that some cylinders transition from spark ignition to compression or spark ignition while others make a transition from compression or compression ignition to spark ignition.

With further reference to 5 activates the routine at 516 an intake and / or exhaust valve with a longer and / or larger stroke via a deactivatable tappet, so that the cylinder makes a transition to spark ignition combustion. Note that activation activation timing may, in one example, be performed after an intake stroke but before an exhaust stroke.

Conversely deactivated at 518 the routine of an intake and / or exhaust valve with a longer and / or larger stroke via the deactivatable tappet for a transition of the cylinder from the spark ignition and into the compression or compression ignition (with an intake and / or exhaust valve with a shorter and / or lower stroke remains active). Note that multiple combustion cycles may be required to produce compression or auto-ignition, and thus spark assisted auto-ignition can be used.

In the above examples, it is thus possible to change combustion modes without requiring a change in the stroke profile; a fairly simple valve deactivation can be used. Such a construction can be advantageous for engines with a bumper and with an overhead camshaft.

Now referring to 6 describes a routine with which different valve operation can be selected within a spark ignition combustion. In particular, the routine at 610 determines whether one or more cylinders of the spark ignition combustion engine are operating. If so, the routine continues 612 to determine if there is any condition for operating one or more spark ignition cylinders with an intake / exhaust valve with a disabled larger stroke. Such conditions may exist due to vehicle deceleration, idling, combinations thereof, or others.

If the deactivation at 612 is selected, the routine continues 614 to deactivate the intake and / or exhaust valve with a larger and / or longer stroke. Otherwise the routine activates at 616 the valve or valves, if not already activated.

Note that the control routines included here can be used with different engine configurations, such as those described above. The specific routine described herein may represent one or more of a number of processing strategies, such as event driven, interrupt driven, multitasking, multithreading, and the like. As such, various steps or functions depicted may be performed in the sequence depicted or in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the embodiments described herein, but is provided for ease of illustration and description. One or more of the steps or functions shown can be repeated depending on the strategy used. In addition, the steps described can graphically represent code that is stored in the computer-readable storage medium in the controller 12 should be programmed.

It is to be understood that the configurations and routines disclosed herein are exemplary in nature and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to the engine types V-6, I-4, 1-6, V-12, push-pull 4-cylinder and others. As another example, various other mechanisms can be used in a system that uses two different valve profiles for each of the valves in a cylinder and selectively deactivating one or more valves to provide the correct flow conditions for compression or auto-ignition combustion. The subject matter of the present disclosure contains all novel and non-obvious combinations and partial combinations of the various systems and configurations and other features, functions and / or other properties disclosed here.

The following claims highlight particular combinations and sub-combinations that are considered novel and not obvious. These claims may relate to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include the incorporation of one or more such elements and neither require nor exclude two or more such elements. Other combinations and partial combinations of the disclosed features, functions, elements and / or properties can be claimed by amending the present claims or by submitting new claims in this or a related application. Such claims, whether broader, narrower, the same, or different in scope of the original claims, are also considered to be included within the subject matter of the present disclosure.

Claims (12)

A method of operating an engine (10) of a vehicle, the engine comprising a cylinder (30) with at least first and second valves (52a, 52b), the method comprising: during a first mode, the first valve (52a) operates actively and the second valve (52b) deactivates during a cycle of the cylinder (30), during the first mode the cylinder (30) operates to provide at least air during an intake stroke can enter the cylinder (30) where the air is mixed with fuel and compressed to achieve auto-ignition; and during a second mode, the first and second valves (52a, 52b) operate actively during one cycle of the cylinder (30), while during the second mode the cylinder (30) operates to allow at least air to enter the cylinder (30) where the air is mixed with fuel and ignited by a spark plug (92); during a transition from the first mode to the second mode, the second valve (52b) is activated and the first valve (52a) is kept active, the first and second valve (52b) inlet valves (52a, 52b) of the cylinder (30) are. Procedure according to Claim 1 , the air being mixed with directly injected fuel during an intake stroke. Procedure according to Claim 1 the air being mixed in an intake manifold (44) via intake port injection (66A). Procedure according to Claim 1 The cylinder (30) further comprises first and second exhaust valves (54a, 54b), wherein during the first mode the first exhaust valve (54a) is active and the second exhaust valve (54b) is deactivated and during the second mode both the first and the second exhaust valve (54a, 54b) are active during one cycle of the cylinder (30). Procedure according to Claim 1 , wherein a stroke profile of the second valve (52b) is longer than a stroke profile of the first valve (52a). Procedure according to Claim 1 , wherein a stroke profile of the second valve (52b) is higher than a stroke profile of the first valve (52a). Procedure according to Claim 1 , wherein a single cam actuates both the first and second valves (52a, 52b). Procedure according to Claim 7 wherein the second inlet valve (52b) is deactivated via a collapsible tappet (214). A system for operating an engine (10) of a vehicle, the engine (10) having a cylinder (30), the system comprising: a first intake valve (52a) in the cylinder (30); a second intake valve (52b) in the cylinder (30); the first inlet valve (52a) and the second inlet valve (52b) being actuated via a common camshaft (130), the stroke profile of the first valve (52a) being different from that of the second valve (52b), an actuating tappet (214 ) of the second valve (52b) has a deactivation device configured to deactivate the second valve (52b), and an actuating tappet (216) of the first valve (52a) from the camshaft (130) under all conditions is operated, whereby the stroke profile of the first inlet valve (52a) is shorter than the stroke profile of the second inlet valve (52b), the stroke profile of the first inlet valve (52a) is smaller than the stroke profile of the second inlet valve (52b), a controller (12) is provided which is active during a first mode with the first intake valve (52a) active and a second intake valve (52b) deactivated during one cycle of the cylinder (30), during operation where the first intake valve (52a ) is at least partially open during an intake stroke, so that at least air can enter the cylinder (30), where the air is mixed and combined with fuel to obtain auto-ignition, and during a second mode, the first intake valve (52a) and second intake valve (52b) operate actively during one cycle of the cylinder (30), during operation the first and second intake valves (52a, 52b) are at least partially open during an intake stroke, so that at least air can enter the cylinder (30) where the air is mixed with fuel and ignited by a spark plug (92), and during a transition from the first mode to the second mode, the controller (12) activates the second valve (52b) and keeps the first valve (52a) active. System according to Claim 9 , further comprising: a first exhaust valve (54a) in the cylinder (30); a second exhaust valve (54b) in the cylinder (30); wherein the first exhaust valve (54a) and the second exhaust valve (54b) are actuated via a common camshaft (132), the stroke profile of the first exhaust valve (54a) being different from that of the second exhaust valve (54b), an actuating tappet (224 ) of the second exhaust valve (54b) has a deactivating means configured to deactivate the second exhaust valve (54b) and wherein an actuating plunger (226) of the first exhaust valve (54a) actuates the camshaft (132) under all conditions becomes. System according to Claim 9 , wherein a stroke profile of the second inlet valve (52b) is longer than a stroke profile of the first valve (52a). System according to Claim 9 , wherein a stroke profile of the second inlet valve (52b) is higher than a stroke profile of the first valve (52a).

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